I have run into a bit of a double-bind for double-blind reviews as an editor. In short, the problem comes down to if reviewers should see an author's Acknowledgements section which cites the grants that supported the work. Either way has problems:
If you let the authors acknowledge their grant during the review process, it is often trivial to find out who is involved in authoring the paper (since the awardees for many grants are published online).
On the converse, if you do not let authors acknowledge funding sources, it is not possible for reviewers to identify potential conflicts of interest or biases in the manuscript.
In general, at least in my core topics, conflicts of interest due to funding is rare, so I am leaning strongly toward having such funding sources omitted. However, I could see it being a significant problem for other disciplines that I collaborate with. Does anyone know of any good rules of thumb, other than "use your judgement, case by case"?
Note: My general stance has been "No Acknowledgements during review" up to this point. However, on considering the issue in light of allowing reviewers to be aware of funding sources, there seem like very rational reasons why you should have this information available to reviewers, provided it could be done without identifying the authors or unfairly biasing the reviewers.